The internet is aflutter with the sensational rumours that Christopher Nolan will oversee Warner Brothers' Justice League expansion, possibly to be directed by Zack Snyder, and potentially starring Christian Bale as Batman. Early word from test screenings of Man of Steel seem to have infused the studio with new-found confidence in their big DC properties, and with the enormous success of The Avengers last summer (it is, after all, the third most successful movie of all time, not adjusted for inflation), a Justice League movie would seem like a no-brainer. But superhero movies are hard enough to pull off well, much less large, ensemble films such as this one. Up until last summer, Bryan Singer's X2 was easily the best and most deftly balanced ensemble superhero film ever made. However, the Justice League movie will face the huge challenge of combining different characters from films directed by various directors with differing styles. Even with Nolan at the helm, it will be a challenge to combine the over-the-top camp of Green Lantern with the dark, brooding hyper-reality of Nolan's Batman series, for example. However, in Nolan (and, hopefully after the release of Man of Steel, in Snyder as well) we trust, and luckily, the two auteurs have a third contemporary they can draw inspiration from: Joss Whedon, who so deftly and successfully balanced the different styles and sentiments of the Marvel super heroes in The Avengers. The Justice League movie has quite an uphill battle ahead of it, but in the meantime, here are five lessons the film could learn from the elements that made The Avengers work so well.